1. Field of the Invention
The present invention relates generally to shielded cords, and more particularly, to braided cords that may be used in leakage current detection and interruption (LCDI) applications, and even more particularly to a braided cord utilizing a conductive foil made of aluminum or copper or any electrically conductive material so as to reduced the coverage of copper braiding typically required in such cords.
2. Description of the Prior Art
Conventional shielded cords for existing leakage current detection and interruption (LCID) application requires 85% coverage of copper strands at a minimum. The rising cost of copper and the need for more economical cords used in LCDIs requires a more economical construction utilizing a conductive coil and reduced copper braiding.
Previous conventional cords do not have the conductive foil and require much higher coverage for the copper braiding. UL requires 85% minimum coverage of copper braiding, which is very expensive due to the increase in copper costs. In the past 18 months, the price of copper doubled, making the cost of conventional braided cord prohibitive in the LCDI application.
Disclosed in the prior art are a number of different cable systems having different core and exterior compositions. For example, U.S. Patent Application No. 20050016755 which was filed in the name of Martinez, et al. on Jan. 27, 2005 for “Dry, water-resistant coaxial cable and manufacturing method of the same” discloses dry coaxial cable resistant to water penetration, made of a core conductor, a dielectric element based on three layers of polymers, and an external conductor and an extruded cover, characterized because it has swellable protecting elements against water penetration placed between the external conductor and the braided cord.
Another example of a cable assembly is taught in U.S. Pat. No. 5,767,442, which issued to Eisenberg, et al. on Jun. 16, 1998 for “Non-skew cable assembly and method of making the same,” which discloses a cable assembly having a plurality of insulated wires that are arranged in groups of one or more wires with adjacent pairs of the groups being interconnected at any given longitudinal location over the length of the cable.
Making such cable water-proof or resistant has also been known in the art. For example, U.S. Pat. No. 6,455,769, which issued to Belli, et al. on Sep. 24, 2002 for “Electrical cable having a semiconductive water-blocking expanded layer” discloses electrical cable having a metal shield and a semiconductive water-blocking expanded layer. Another such example is shown in U.S. Pat. No. 3,589,121, which issued to Mulvey on Jun. 29, 1971 for “Method of Making Fluid-Blocked Stranded Conductor,” which discloses an insulated stranded conductor manufactured by first coating a wire filament or strand, and then forming a stranded conductor with the coated filament as the center strand, then applying an outer insulation over the resulting stranded conductor under sufficient pressure to at least partially fill the interstitial spaces between the strands.
Disclosed in U.S. Pat. No. 6,369,328, which issued to Munakata on Apr. 9, 2002 for “Heat dissipating device for transmission line, transmission line with heat dissipating device, and method for fitting heat dissipating device to transmission line” is a braided heat conducting wire heat dissipating belt wound around an outer circumference of an already strung aerial line or jumper so as to increase the heat dissipation effect of the surface of the aerial line so as to enable the capacity of a permissible power supply of the already existing aerial line to be increased.
A number of prior art references are directed to fence wire construction. For example, U.S. Pat. No. 5,036,166, which issued to Monopoli on Jul. 30, 1991 for “Electric fence line” discloses an electric fence line formed of strands of a high strength and high visibility electrically insulative material, which have been woven, twisted, or braided, together with at least one highly electrically conductive low electrical resistance metal strand, such as copper wire, and at least one high-strength metal strand of higher electrical resistance, such as stainless steel. Similarly, U.S. Pat. No. 4,905,969, which issued to Kurschner, et al. on Mar. 6, 1990 for “Electric fence wire construction” discloses an electric fence wire construction is made by plying or weaving coated supporting members, preferably fiberglass coated with polyvinyl chloride, with conducting members, preferably aluminum.
Yet another example is discussed in U.S. Pat. No. 3,067,569, which issued to Kelley Jr. on Dec. 11, 1962 for “Electrical Conductors and Methods of Manufacture Thereof.”
Similar processes of manufacture are also used in other applications, as is disclosed in U.S. Pat. No. 6,601,377, which issued to Tsukamoto on Aug. 5, 2003 for “Gland packing materials made from expansive graphite, gland packing made from expansive graphite made from the materials, and a producing method of gland packing made from expansive graphite,” and which teaches the use of gland packing materials made from expansive graphite, gland packing made from expansive graphite made from the materials, and a producing method of gland packing made from expansive graphite.
As shall be appreciated, the prior art fails to specifically address either the problem or the solution arrived upon by applicant.